Machine Elements in Mechanical Design Essay Example for Free

Machine Elements in Mechanical Design Essay Answers to Selectecj Problems Given here are the answers to problems for which there are unique solutions. Many of the problems for solution in this book are true design problems, and individual design decisions are required to arrive at the solutions. Others are ofthe review question form tor which the answers arc in the text ofthe associated chapter It should also be noted that some ofthe problems require the selection ot design factors and the use of data from charts and graphs. Because of the judgment and interpolation required, some ofthe answers may be slightly different from your solutions. AISI 1080. 28. AISI 5160 OQT 1000 is a chromium steel, having nominally 0. 80 percent chromium and 0. 60 percent carbon, a high carbon alloy steel. It has fairly high strength and good ductility. It was through-hardened, quenched in oil, and tempered at 1000Â °F. 29. Yes. with careful specitlcadon ofthe quenching medium. A hardness of HRC 40 is equivalent to HB 375. Appendix 3 indicates that oil quenching would not produce an adequate hardness. However, Appendix 4-1 shows that a hardness of HB 400 could be obtained by quenching in water and tempering in 700Â °F while still having 207f elongation for gciod ductility. 3. AISI 200 and 300 series 34. A hardness of 750 HB is extremely hard and characteristic of as-quenched high alloy steels, 15. The HRB scale is normally limited to HRB 100. 16. The HRC hardness is normally no lower than HRC 20. 17. The given relationship between hardness and tensile strength is only valid for steels. 18. Charpy and Izod 19. Iron and carbon. Manganese and other elements are often present. 20. Iron, carbon, manganese, nickel, chromium, molybdenum. 21. Approximately 0. 40 percent. 22. Low carbon: Less than 0. 30 percent

Critique of A Biography of the Continent Africa by John Reader Essay

A Critique Abstract   Ã‚  Ã‚  Ã‚  Ã‚  A Biography of the Continent Africa, written by John Reader is an extensive chronological and topical study of Africa. Support reveals the earliest corroboration of the existence of human antecedents was discovered in east Africa at locations scattered north and south of the equator. The discovery shows fossilized bones, stone tools, and the most significant of all, a trail of footprints in the preserved mud pan surface. The trail shows they walked across the pan more than three million years ago toward what is now called the Serengeti plains. â€Å"These human ancestors made their living from and among the animals with whom they shared the landscape. They were neither diminutive, large nor numerous- who existed nowhere else on earth for over four millions years. The modern human species, Homo sapiens, with large brain and a talent for innovation, evolved from ancestral stock towards the end of that period.† (p.1)   Ã‚  Ã‚  Ã‚  Ã‚  Africa, also know as the â€Å"dark continent† encompasses the second biggest landmass but it has only twenty-two percent of the earth’s land surface. (The United States could fit within the Sahara desert alone). About a 100,000 years ago family groups left the continent for the first time and progressively colonized the rest of the world hence â€Å" the cradle of civilization† term for Africa. The Reader states that it was estimated that â€Å"about 1 million people inhabited African when the emigrants left the continent 100,000 years ago†¦and by A.D. 200 numbers are said to have risen to 20 million- of whom more than half lived in North Africa and the Nile valley.† (p.5) Book Organization Overall composition The book contains eight parts, which have several chapters each that outline the history of Africa from the first knowledge of the continent to the â€Å"Dreams and Nightmares† (p.663) along with a large number of references, notes, appendixes, preface, and prologue. The book is a fine documented copulation of fact and information that any Reader from the novice of the general public to the serious history student would find as a great tool for their enlightenment and study. (Part 1) Starts with the known beginning history of the continent as well as the first recognized history of humankind. Africa is the Earth’s most ancient and perm... ...around the world. Representative countries The regions, of the continent have been uniformly represented by the text. There is however, missing information on a few of today’s countries in the book, this might be the result of the Copyright or the change in the status and control of these countries, as a consequence of internal struggling for power and Sovereignty. To date there are thirty- three different countries including the Canary Island within the continent. Conclusion Africa is continent with few rivals in size or in a history as ancient as the beginning of the World, it would be very difficult indeed to cover every detail and aspect. The text of the book is a marvelous and thought-stimulating piece of work. A cornucopia of information, rich in diversity, evolution, and triumphs for the environment of a continent and the legacies of her people. The renewed interest for conservation of land and animals within the interior of Africa shall leave for the world and future generations a magnificent place to live and visit. Like the Alaskan wilderness of North America it is truly â€Å"God’s country†.

The 7 Habits of Highly Effective Teens

You ever wish there was a step-by-step guide to life? Something that can help you improve your self-image, build friendships, and most importantly achieve your goals? In The 7 Habits of Highly Effective Teens, it guides you to live up to your potential by inspiring and motivating you with positive strategies. In addition, this book is filled with quotes and stories about real people in real scenarios, making this relatable to any age group facing difficult situations. â€Å"Look at this as an opportunity to grow† (Covey 57). I have always been a huge procrastinator.I would put off my schoolwork until the last minute and then cram it all the night before. And to top that off I was also a Yes-man so I would worry about my friends’ work rather than my own. Definitely not a good combination. You can obviously notice the lack of performance I showed, especially in my grades. I went from being a straight â€Å"A† student, to a â€Å"B and C† average. I didn†™t pay much attention to it though because everyone else had the same problem as well. I was surrounded by procrastinators, leading me to think that what I was doing was acceptable.It was not until I started to read The 7 Habits of Highly Effective Teens that I noticed my bad habit. I didn’t even consider it a habit until I read a part in the book and realized that it sounded so familiar. Like if they had used my own personal experience and wrote it down word by word. I never really put any thought to how a simple thing can cause such an effect to me, and not just in my school life, but also my personal life. It was that moment when I promised myself to change. Change into a better me because I am capable of better. I am capable of being a Prioritizer, instead of a Procrastinator.I am capable of living a healthy and balanced life. I am capable of achieving my lifetime goals and continuously live up to my full potential. But how can I make a change? Where do I even begin? Wh en my teacher introduced me to this book, I had finally found the solution to my problems. Because unlike any other book, this book feels like it speaks directly to me. Like if it was my very own personal mentor, but even better because it’s in the comfort of my own hands. It not only pointed out my flaws, but also suggested various forms of how I can make a change. I am habit† (Covey 1). Little by little, I was slowly improving my way of life. I highly recommend everyone to read this book, even if you feel that you’re perfectly fine. Just read it and if you can relate to any of the stories used in the book, then you know that you have to fix something in your life. Take it as a blessing. â€Å"These problems are real, and you can’t turn off real life. So I won’t. Instead, I’ll give you a set of tools to help you deal with real life. What are they? The 7 Habits of Highly Effective Teens† (Covey 5).

Coral Reef - 799 Words

SangHoon Kang Period 5 AP Environmental Science Mr. KrupensHow Can We Preserve the World’s Coral Reefs Critical Thinking Questions and AnswersHow does the current state of the world’s coral reefs illustrate each of the six key themes of this book? Human population: With current state of coral reefs, we are definitely valuing the quality of life of a person living today because of the fact that coral reefs are indirectly, sometimes directly, destroyed by over fishing using the methods such as using dynamites or cyanides which causes corals to be destroyed and damaged. However we have to start thinking about the future generations. Sustainability: With current state of coral reefs, the persistence of these resources for future†¦show more content†¦As said, coral reefs are associated with about 1 million marine organisms and 15% of the entire worldwide catch is reef fish. In order for him to meet his needs and preserve coral reefs is to limiting himself on the amount that his catching per year, but about to making living out of it. Also he should not use dynamite and cyanide methods to catch fishes. In addition, he should definitely be aware about not to destroy or pry apart the coral reefs while fishing in any methods that he choose to. What things can you do in your everyday life to contribute to the preservation of coral reefs? For me, as a student, all I can contribute to the preservation of coral reefs are to conserve water (less waste water dumped in ocean), reduce pollution (help reduce ocean warming), dispose my trash properly (no water is polluted), use only ecological or organic fertilizers (so ocean is not polluted), volunteer for a coral reef cleanup, practice safe and responsible diving and snorkeling (so no coral is harmed or destroyed), and especially spread theShow MoreRelatedCoral Reefs And Coral Reef1180 Words   |  5 Pages Coral reefs in Belize have declined in abundance over the past decade. The reefs have experienced massive losses due to many local and global stressors such as bleaching, disease, sewage, overfishing, climate change, and tourism damage. After Hurricane Iris in 2001, the coral reef in Belize was left for the dead due to no growth. Direct impacts such as hurricanes are associated with the loss of architectural complexity of coral habitats. The loss of this coral reef complication drives the declineRead MoreThe Reefs And Its Effects On The Coral Reefs1608 Words   |  7 Pagesthere are many coral reefs. This island I chose to look at, is called Desecheo Island or Isla de Desecheo. It s just of the coast of Puerto Rico. The coral reefs in the island are continental reefs according to geomorphologists( people who study physical features of the Earth’s surface). It is a fringing reef around the coast of the island and a shelf reef beyond that. In the fringing reef, the depth of th e reef is mixed between shallow and deep. When it gets near the shelf reef areas, the depthRead MoreCoral Reefs : The Ecosystem860 Words   |  4 PagesCoral reefs are an essential component to the ecosystems in Hawaii. Coral reefs are comprised of numerous Cnidarian species that grow sympatrically to form structured colonies. Coral reef colonies support a wide range of marine wildlife. The marine animals utilize coral reefs as their habitat, as a source of food, and as a catalyst for community interactions. Coral reef communities that are well established are known to be highly biodiverse. Coral reefs are known as the tropical rainforests of theRead MoreImminent Threats to Coral Reefs996 Words   |  4 PagesCoral reefs are fragile ecosystems, and even a slight change in their marine habitat could drastically impact the corals, and other marine life too. One of the main threats to the reefs is climate change. As global warming occurs through out the world, the ocean waters will also start to get warmer, which is what is known as ocean warming. Even 2 degrees Celsius change in the water can have a massive impact on the corals. This is because the corals can feel this slight change and will start to feelRead MoreCoral Reefs Essay722 Words   |  3 PagesCoral reefs are very diverse ecosystems. They are â€Å"the rainforest of the sea†. 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Coral reefs act as a natural barrier that protectsRead MoreThe Human Impacts Of Coral Reefs Essay1383 Words   |  6 Pagesless than 1% of the world oceans, the coral reefs are ancient animals comprising of thin calcium carbonate deposits within the photic layer. Aside from its biologically diverse ecosystems, coral reefs are major source of food for millions and provides habitats and nursery areas for many marine organisms. Coral reefs also act as a physical buffer to protect the coastlines from tropical storms and erosion. In addition, many local communities rely on coral reefs to generate an income through activitiesRead MoreCoral Reefs Need Help2489 Words   |  10 Pagestaking care of endangered coral reefs now! World government leaders should establish laws to protect them. People may ask, â€Å"If coral reefs are in such danger, why don’t we fix the problem since they provide benefits for the whole world?† Frankly, it’s not that simple. Protecting enda ngered coral reefs will provide the whole world with long lasting benefits. To figure out how to solve the problem, we must start with the benefits they provide for humans and nonhumans. Coral reefs support 128 corallivorousRead MoreThe Endangerment Of Coral Reefs1685 Words   |  7 Pagesof Coral Reefs When people, tourists especially, ask themselves what is one of the most memorable moments they have experienced in the Florida Keys, the first thing that comes to mind is the ocean. Not only the ocean in general, but what is beyond, or in other words, â€Å" what is beneath?†. Far in the aquamarine water there is another world that people do not even know about, where many different species of life come together and form a place of peace and beauty. This world is called a coral reefRead MoreEssay on â€Å"The Sad Fate of Coral Reefs†1077 Words   |  5 Pageslies with the â€Å"Rainforests of the Sea†, the coral reefs. Coral reefs are the most diverse and biologically richest of all marine ecosystems. As with almost every ecosystem and its members, coral reefs provide several ecosystem services. For instance, coral reefs serve as natural barriers against hurricanes and catastrophic storm surges, their chemicals may treat diseases, and they are a nitrogen fixation. On of the most important functions of coral reefs are that they are a major source of food for